SEATTLE – Looking to reinforce their bullpen for Monday’s doubleheader with the A’s, the Mariners reinstated right-handed reliever Erik Swanson from the 10-day injured list and optioned lefty Aaron Fletcher back to their alternate training site.

The club also activated utility man Tim Lopes as the 29th man for Monday’s games, as teams are allowed to add an extra player to the 28-man roster for doubleheaders.

The Mariners are still without shortstop J.P. Crawford, who missed the past three games after being placed on the bereavement list following a death in his family.

Manager Scott Servais said Crawford likely won't be able to rejoin the team until later in the week. Players can spend a maximum of seven days on the bereavement list.

“He’s working through some things at home, back in California with his family,” Servais said. “I’m expecting he could be back here in the next few days, but do not have an exact time yet. When he does come back, he’ll have to go through the [COVID-19] intake testing and things like that.”

Swanson has been sidelined since Aug. 20 with a right forearm strain. The 26-year-old made six appearances before going on the injured list, allowing nine runs on seven hits -- including three home runs -- in 5 1/3 innings for a 15.19 ERA.

But Swanson has been throwing well at the alternate site in Tacoma and will join Seattle’s 11-man bullpen, which needed to cover seven innings in Sunday’s 7-3 win over the D-backs when starter Justin Dunn lasted only two frames.

“The reports are Swanny has been throwing great,” Servais said. “The velocity has been up, and secondary pitches are very good. But he’ll be limited. He can probably give us an inning and we’ll see how he looks.”

Servais said it’s possible that right-hander Brandon Brennan could rejoin the club in the next day or two as well. Brennan has been sidelined since early in Summer Camp with a strained left oblique, but he is eligible to come off the 45-day injured list now, and he has also been throwing well at the alternate site.

Fletcher, 24, opened his career with three scoreless appearances after being called up in late August, but he's allowed six hits and six runs with four walks in two innings over his past three outings, and he has a 12.46 ERA overall. The lefty is the Mariners’ No. 21-ranked prospect, per MLB Pipeline, but had never pitched above Double-A ball until his promotion to the Majors this season.